1. Field of the Invention
The present invention relates to a production apparatus which is provided with a robotic arm.
2. Description of the Related Art
In recent years, an assembly production apparatus is demanded which achieves an assembly operation by a robotic arm in place of the assembly operation by a human hand. In the assembly operation by the human hand, in order to efficiently cope with production having a wide variety of products in small quantities, a human cell production system is introduced which removes a conveyor, conveys a workpiece by a human hand, and is responsible for a fixed process; and the human cell production system is rearranged according to a production item. A robot cell is a cell in which one human cell in this human cell production system is replaced with the assembly production apparatus by the robotic arm, and there is a production apparatus described in Japanese Patent Application Laid-Open No. 2011-240443, for instance.
The robotic arm of these production apparatuses has a tool such as a camera and a hand provided at the tip portion thereof, and control signals and image signals to be transmitted to the tool and the hand are usually transmitted/received thereto/therefrom, through cables built into the robotic arm.
However, the cables which are built into the robotic arm are exposed to a severe moving condition. Among the cables, a high-speed communication line which is used for the control and transmission of an image needs a shield and the like, and accordingly has such a drawback that a durability life is short.
In addition, there is the case where the camera or the like becomes unnecessary depending on an assembly process, and is required to be capable of being easily removed. Usually, in such a case, an image communication cable of the camera is routed from the outside of the robotic arm, and accordingly when the robot cell is rearranged, there have been such drawbacks that a complicated operation such as routing of a cable is needed, and a lead time for a start of the apparatus becomes long.
On the other hand, a method is known which improves the drawbacks by abolishing the image communication cable and exchanging such a high-speed signal through a wireless communication in a production apparatus described in Japanese Patent Application Laid-Open No. 2006-105782, for instance.
However, when the wireless communication is performed in the above described production apparatus such as the robot cell, the apparatus results in performing a large number of wireless communications in an extremely narrow area, and accordingly frequency channel for preventing electromagnetic waves from causing interference between adjacent production apparatuses becomes insufficient.
In recent years, in particular, a tool control signal of a camera, a robot hand and the like which are used in FA has been increasingly required to increase the speed, and in order to cope with the increase, a wireless unit is required to take measures of changing the frequency to a high band for securing the band, and the like.
In millimeter wave communication by a band of 60 GHz which is often used in high-speed wireless communication of an image, for instance, the number of channels which can be legally permitted is only four channels. In such a case, when there are four or more other production apparatuses which are adjacent to the production apparatus, there has been the case where the production apparatuses cannot be discriminated by the frequencies.
For this reason, when the wireless communication is heavily used in the production apparatus such as the robot cell, which has been described above, the interference of the communication occurs among the adjacent production apparatuses, and there have been problems that an error occurs due to a great decrease of a transmission speed of the wireless communication and an increase in a waiting time of the wireless unit, and that the production apparatus stops.
An object of the present invention is to provide a production apparatus which can stably perform wireless communication while avoiding the interference of communication with other production apparatuses.